A multidimensional data space combines stored data from a number of data sources. An example of a multidimensional data space is a relational database. A dimension of a data space is a collection of references to stored data. In the context of relational databases, such references to stored data are often called attributes, or cells. It is generally recognized that many multidimensional data spaces contain no stored data at the intersection of two or more dimensions of the data space—such data spaces are referred to as sparse.
Various languages and syntaxes have been developed to query multidimensional data spaces. Some query languages support the use of expressions which, when evaluated, transform and/or perform calculations based on stored data. Query performance and the presentation of query results are often negatively impacted by sparse data spaces, especially when expressions are present.